利用SQL选择表employee 中第6高的薪水？

[chding]

一到Autodesk的笔试题，网上的答案是：
SELECT TOP 1 salary FROM
( SELECT DISTINCT TOP 6 salary FROM employee ORDER BY salary DESC) a
ORDER BY salary

不懂这个a是什么？翻了数据库的书，没看到这种用法

[internetroot]

就是为( SELECT DISTINCT TOP 6 salary FROM employee ORDER BY salary DESC)取个别名，别名为a。

[internetroot]

就是为( SELECT DISTINCT TOP 6 salary FROM employee ORDER BY salary DESC)这个查询取个别名，别名为a。取别名的好处就是多次调用查询( SELECT DISTINCT TOP 6 salary FROM employee ORDER BY salary DESC)可以用a代替。

[fzcheng]

[Quote=引用 2 楼 Internetroot 的回复:]
就是为( SELECT DISTINCT TOP 6 salary FROM employee ORDER BY salary DESC)这个查询取个别名，别名为a。取别名的好处就是多次调用查询( SELECT DISTINCT TOP 6 salary FROM employee ORDER BY salary DESC)可以用a代替。
[/Quote]
把( SELECT DISTINCT TOP 6 salary FROM employee ORDER BY salary DESC)看成个数据集理解就可以了。

[chding]

哦，明白，多谢

[cxmcxm]

--a为前面括号查询结果的表别名.
--即
SELECT TOP 1 salary FROM 
      ( SELECT DISTINCT TOP 6 salary FROM employee ORDER BY salary DESC) as a 
ORDER BY salary 

[regithanhu]

别名而已！就比如我们常用 select * from temp as a
a就temp的别名

[yinqi025]

取个别名而已

[flairsky]

没这个a，语法通不过

[LIHY70]

a别名

[utpcb]

别名咯 你可以不要哈哈

[lff642]

表的别名..